Print cooling fan not coming on

I am able to turn the print cooling fan on manually in the DWC, but its not turning on by itself at layer 3 like it should. I'm reinstalling my slicer now. is there anything the Firmware that could contribute to this? should I reinstall it if reinstalling my slicer doesn't do the trick?The tech support from S3D just give canned answers that don't really fit the problem.

Here are some reasons why the print cooling fan might not be coming on:

1. Bad connection in the wiring. It might be OK in some head positions and not ok in others.

2. If the slicer is commanding the fan to turn on at less than full speed, you might need to change the PWM frequency. Lower frequency may help. Or you may need to use a longer blip time. Both of these are parameters in the M106 command. Some fans just don't like PWM.

3. If your printer is a delta with magnetic arm joints, some fans don't work properly in the presence of the magnetic fields from the joints.

1. all new wiring and I have already replaced the connectors
2. I have the blip to full speed enabled, however I can still turn the fan on @ 3% manually in the DWC and it comes on. it doesn't even show that it should be on in the DWC, BOTH are at 0. its like it never got the command.
3. CoreXY

If you can turn it "manually" through DWC then logic would dictate that the slicer isn't putting the M106 command in the file (or that it is putting M106 but with other parameters which prevent the fan from running). In your OP you state that the fan ought to come on at layer 3, so take a look at the gcode file and see if there is an M106 soon after the G1 Znnn (where nnn corresponds to the height for layer 3). If the M106 command is there, what comes after it? Full speed would be M106 S255.

I think I got it, it is mapped to fan 0, but I only had fan 2 available for PWM. I got a new board so I have have this one repaired (have to find someone, my hands shake too badly) when I swapped everything to the new board I put all the fans exactly where they were. so fan 0 got triggered, but since it wasn't there, no cooling fan. in future if I have a problem with a fan o can I map the firmware to tell it to use say fan 1 or fan 2? and one for the suggestion box, make the fans match in the firmware and the DWC having 0,1,2 and 1,2,3 is annoying.

going to do a test print now to verify this, but the g-code you gave me earlier seems to work. thanks